Preparation of tungsten sulfides by sol-gel processing

Tungsten sulfides were synthesized by reaction of different tungsten alkoxides and hydrogen sulfide in toluene. The reaction was performed ill toluene solution at room temperature. Tungsten ethoxide yielded a brown black gel, while tungsten dichloride ethoxide produced a brown-black colloidal powder. The W/S at% ratios were 1:2.7 and 1:1.4 in the eel and powder, respectively. Both sol-gel products were amorphous materials. The gel appeared to be highly viscous liquid formed from spherical colloidal particles connected into a three-dimensional network. However. the powder consisted of loose colloidal particles whose radii were in the range 0.5 to 1 mu m. (C) 1997 Elsevier Science B.V.